A mountain lion on the hill behind Rovina Lane, in the southwest area of Petaluma, was reported to police at 9:20 p.m. on Thursday.

The reporting party said that the mountain lion was about the size of a very large dog and was not aggressive, said Sgt. Jim Stephenson of the Petaluma Police Department.

Officers came to the scene, and were not able to locate the mountain lion. No other people reported seeing it, Stephenson said.